1. Field of the Invention
This invention relates to the utilization of engine exhaust heat to vaporize hydrocarbon components of fluids taken from oil and gas wells in order to use said vaporized hydrocarbons as fuels, particularly for internal combustion engines located in remote petroleum field operations.
2. Description of the Prior Art
The prior art has long recognized that the entrained vapors of and/or the low-boiling constituents of many petroleum wellstream fluids (e.g., paraffinic hydrocarbons up to hexane, and particularly propane) make excellent fuels for heat engines in general and internal combustion engines in particular. It is also well known that as the temperature applied to such wellstream fluids is increased the character of the compounds obtained from such fluids, particularly crude oil, also changes. The paraffins are rapidly displaced in predominance by other types of hydrocarbons which are not directly usable as fuels, particularly for internal combustion engines. The prior art has also long recognized that heat from an engine's exhaust can be used to separate low-boiling petroleum constituents which make good fuels from higher boiling constituents which do not make good fuels, at least for internal combustion engines. Those devices which use exhaust heat for such purposes are chiefly concerned with carrying out two main functions: (1) separating petroleum products from those foreign substances, particularly water, that usually accompany the petroleum products (often in the form of emulsions) in petroleum wellstream fluids and (2) separating lighter hydrocarbons from the heavier ones so that the former can be used as fuels and thereby replace the more expensive gasoline, diesel oil and propane fuels which otherwise must be hauled to the remote locations where petroleum field operations usually take place. Patents disclosing such prior art devices include:
U.S. Pat. No. 2,284,809 which teaches use of exhaust heat to obtain non-cracked diesel oils, kerosene or gasoline from a pure crude oil stream such as those pumped through oil pipeline systems. Separation of oil and water mixtures or emulsions is not taught or suggested in this patent;
U.S. Pat. No. 2,656,925 teaches the use of engine exhaust heat to facilitate the breaking of oil/water emulsions by lowering viscosities and using differential coefficients of expansion of the components of a wellstream fluid. The use of a heater element having a large surface area purposely located at the oil/water interface is emphasized in order to carry out the disclosed emulsion breaking function. The oil/water interface is adjusted to the level of the heater element by a siphon and drainage system;
U.S. Pat. No. 3,892,276 also teaches a method of breaking down water/paraffin emulsions to facilitate separation of water from a wellstream fluid. Exhaust gases flow counter to the flow of oil. Vaporization of the oil for use as a fuel is not disclosed; and
U.S. Pat. No. 2,698,055 teaches a process for generating fuel gases from a pure oil stream using engine exhaust heat. Again, the matter of separating impurities such as water from the oil is not addressed.